Floral Volatiles in Natural Populations of <i>Paeonia lactiflora</i>: Key Components and Cultivar Differential Analysis

Floral scent serves as a key criterion for evaluating the ornamental value of flowering plants. Herbaceous peony (Paeonia lactiflora Pall.), a traditional Chinese ornamental species, is valued for its vibrant coloration, intricate floral morphology, and positive cultural symbolism. In this study, dynamic headspace adsorption coupled with gas chromatography-mass spectrometry was employed to analyze volatile organic compounds (VOCs) in flowers of 120 herbaceous peony cultivars at the half-opening stage. We detected 86 VOCs, comprising 25 aromatic compounds (79.70%), 21 hydrocarbons (10.51%), 29 terpenoids (8.37%), 7 fatty acid derivatives (1.03%), and 4 heterocyclic compounds (0.38%). The cultivar ‘Dr. Alexander Fleming’ demonstrated the highest total VOC content, followed by ‘Yuezhao Shanhe’ and ‘Daiyu’. The top five cultivars based on principal component analysis composite scores were ‘Shajin Guanding’, ‘Many Happy Returns’, ‘Edulis Superba’, ‘Huicui’, and ‘Madame de Verneville’. The volatile compositions of these cultivars showed statistically representative characteristics. Aroma activity value analysis revealed 22 key aroma components (e.g., 3-hexen-1-ol, acetate, (Z)-, limonene, (E)-β-ocimene) and 15 modifying components (e.g., methyl hexanoate, α-pinene, benzaldehyde). Domestic cultivars exhibited greater VOC diversity and higher content levels compared to introduced cultivars, with introduced cultivars demonstrating more pronounced compositional variation. Introduced cultivars primarily released nonanal and 1,4-dimethoxybenzene, associated with fruity-sweet notes, whereas domestic cultivars predominantly released 1,4-dimethoxybenzene and phenylethanol, characterized by sweet-floral aromas. Aromatic compounds primarily contributed to the overall aroma, with terpenoids as secondary contributors. This study systematically characterized the floral aroma components of herbaceous peony, providing a theoretical foundation for germplasm resource utilization in cut flower production, essential oil extraction, and aromatherapy applications.